This is a plugin for the Google Protocol Buffers compiler protoc that generates code to implement json.Marshaler and json.Unmarshaler using protojson.
This enables Go-generated protobuf messages to be embedded directly within
other structs and encoded with the standard JSON library, since the standard
encoding/json
library can't encode certain protobuf messages such as
those that contain oneof
fields.
go get github.com/mitchellh/protoc-gen-go-json
Also required:
Define your messages like normal:
syntax = "proto3";
message Request {
oneof kind {
string name = 1;
int32 code = 2;
}
}
The example message purposely uses a oneof
since this won't work by
default with encoding/json
. Next, generate the code:
protoc --go_out=. --go-json_out=. request.proto
Your output should contain a file request.pb.json.go
which contains
the implementation of json.Marshal/Unmarshal
for all your message types.
You can then encode your messages using standard encoding/json
:
import "encoding/json"
// Marshal
bs, err := json.Marshal(&Request{
Kind: &Kind_Name{
Name: "alice",
},
}
// Unmarshal
var result Request
json.Unmarshal(bs, &result)
The generator supports options you can specify via the command-line:
enums_as_ints={bool}
- Render enums as integers instead of strings.emit_defaults={bool}
- Render fields with zero values.orig_name={bool}
- Use original (.proto file) name for fields.allow_unknown={bool}
- Allow messages to contain unknown fields when unmarshaling
It also includes the "standard" options available to all protogen-based plugins:
import_path={path}
- Override the import pathpaths=source_relative
- Derive the output path from the input path- etc.
These can be set as part of the --go-json_out
value:
protoc --go-json_opt=emit_defaults=true:.
You can specify multiple using a ,
:
protoc --go-json_out=enums_as_ints=true,emit_defaults=true:.
Alternatively, you may also specify options using the --go-json_opt
value:
protoc --go-json_out:. --go-json_opt=emit_defaults=true,enums_as_ints=true